Patent Application
20160008995
This application claims priority from and incorporates by reference German Patent Application DE 10 2014 105 352.4 filed on Apr. 15, 2014.
The present invention relates to a device for cutting a frozen food product strand into slices.
The method and the device described supra are already known from practical applications. It has proven helpful to saw frozen food products for portioning. Typically band saws are used for this purpose wherein operating them is rather risky for the operator since the cutting material has to be supported by hand so that businesses have to pay high insurance premiums. Since the saw blades are rather thin the loss of cutting material caused by the cutting process is insignificant.
Furthermore circular saws are known for portioning frozen food products wherein large monolithic blocks with frozen material are fed to a plurality of circular saw blades which cut the blocks into strips with identical sizes. Thus, a blade plane of the circular saw blades is respectively parallel to a feed direction of the frozen blocks.
Furthermore a cutting device in particular for fish products is known from EP 0 429 711 B1 which allegedly facilitates weight precise cutting. With this cutting device the cutting process can also be performed transversal to a conveyor belt, thus transversal to the feed direction. Thus a respective cutting tool is lowered from a top side of the conveyor belt into the food product which is thus cut. In order to continuously produce plural portions of the food product a linear oscillating movement of the cutting tool is performed wherein the cutting tool continuously rises and descends wherein the food product is cut during each descent. A linear oscillating movement of the cutting tool between two extreme positions requires a directional reversal of the cutting tool which generates high inertial forces which can cause the cutting device to run rough. Furthermore a required machine configuration is rather complex.
A device for sawing block shaped frozen food products is known from DE 1188250 which teaches using circular saw blades instead of band saws. However, since an increasing diameter of the circular saw blades necessitates an increase in blade thickness for safety reasons this would soon lead to a blade thickness which is high enough to render the sawing loss unacceptable so that a sawing device is proposed in the publication document recited supra which includes two saw blades that cut in the same plane and which are driven in opposite directions at identical speeds. In order to able to saw a food material block with the thickness D thus circular saw blades are used that engage from opposite sides and which respectively only have to penetrate half the thickness D of the block in order to eventually produce two saw gaps that extend over the entire thickness D. The two circular saw blades of the known device are stationary and the food product block to be sawed is moved forward in its longitudinal direction parallel to a plane of the circular saw blades. In order to generate more than one saw cut through the food product block in a single feed stroke plural circular saw blades are arranged offset in an axial direction respectively on a circular saw blade shaft.
DE 10 2010 002 279 A1 discloses a machine in particular for cutting meat into slices, wherein the meat can also be partially frozen or completely frozen. Thus, a circular blade is supported at a swing arm wherein the blade is supported at the swing arm so that the blade is drive able in rotation, wherein the swing arm rotates about a rotation axis that is arranged outside of the cutting cross section and that is oriented parallel to a feed device (orbital drive). In order to generate a saw effect the ratio of the speed of the circular blade to the speed of the swing arm is at least 6 to 1, advantageously at least 8 to 1 for frozen food products. However, the known machine is a cutting machine and no circular saw since no chips are generated during a separation process and the circular blade does not have any teeth that develop a chipping effect in a circumferential direction of the blade and which can cause a material removal from the cutting gap. Thus, the machine according to DE 10 2010 002 279 A1 is of a different genus than the subject matter of the instant application.
Thus, it is an object of the instant invention to improve the method and the device described supra so that the recited problems do not occur.
The object is achieved by a device for cutting a frozen food strand into slices, the device including a machine frame; a cutting device with a cutting tool configured as a circular saw blade supported in or at the machine frame, wherein the cutting tool is rotatable about its center axis and moveable in a cutting plane defined by the circular saw blade; and a feed portion for the food product to be cut from which feed portion the food product is moveable towards the cutting device so that successive slices are cutable from the food product wherein the food product is moveable in the feed portion into a feed direction which extends perpendicular to the cutting plane, wherein the circular saw blade is supported drivable in rotation at an arm that is supported in or at the machine frame, and wherein the circular saw blade continuously rotates or oscillates with the arm about a rotation axis of the arm which rotation axis is fixated at the machine frame.
The object is also achieved by a method for cutting a frozen food product strand into slices, the method including the steps inserting the food product to be cut in a feed portion of a device for cutting; moving the food product out of the feed portion forward to a cutting device of the device so that successive slices are cut off by a cutting tool configured as a circular saw blade from the product at its forward end; rotating the circular saw blade about its center axis and moving it in a cutting plane defined by the circular saw blade; and moving the food product in a feed direction that extends perpendicular to the cutting plane during feeding, wherein an arm which supports the center axis of the circular saw blade is rotated about a rotation axis that is fixated at the machine frame, or wherein the arm performs an oscillating movement about the rotation axis.
The object is achieved by a device in which the circular saw blade is supported drive able in rotation at an arm that is supported in or at the machine frame and wherein the circular saw blade continuously rotates with the arm about a rotation axis of the arm (oscillates). This way the saw blade is either always moved circumferentially in one direction so that a directional change that is required for a translatoric back and forth movement is omitted. The arm that can also be designated as swing arm performs a circumferential movement about its rotation axis that is fixated at the frame. The saw blade is typically arranged at an end of the arm which end is arranged opposite to the rotation axis that is fixated at the frame and the saw blade additionally rotates about its own axis of rotation. A cutting device of this type runs smoothly and has a favorable configuration from a cost end and design point of view. Alternatively the swing arm can also be moved in an oscillating manner which implements a space saving motion without limiting a maximum possible cutting cross section. Additionally the food product in both alternatives is not moved by hand like in the prior art but the feeding of the food product is also provided in an automated manner which increases operational safety, reduces a risk of injury and eventually has a favorable effect on insurance premiums.
According to a particularly advantageous embodiment of the device according to the invention a thickness of the circular saw blade at least in a portion of teeth, advantageously in an annular portion which extends from an outer diameter of the circular saw blade by 20 mm to 30 mm radially towards a center axis is less than 2 mm, advantageously less than 1.8 mm and further advantageously less than 1.7 mm, additionally or alternatively the diameter of the circular saw blade should be more than 500 mm, advantageously more than 550 mm, further advantageously more than 600 mm.
During the sawing process pieces of the food product are cut out in a width of the individual teeth of the saw blade. These pieces are waste material and are not used in the food product. Therefore the intention is to keep the sawing losses as small as possible. So far mostly band saws were used. The main reason being that their saw blades are characterized by a small thickness between 0.8 mm and 1.2 mm. Contrary thereto known circular saw blades have a thickness of approximately 4 mm for technical reasons which renders using a circular saw for cutting frozen food products uneconomical due to the high saw cutting loss. Even considering that band saws cause high insurance premiums due to the high risk of injury band saws remain more economical than circular saws that are known in the art.
By reducing the thickness of the circular saw blade in a relevant outer portion of the circular saw blade to half the prior thickness at the most or even less significantly reduces the sawing loss so that using a device according to the invention becomes interesting in particular for safety reasons.
Arguments against reducing the thickness of the circular saw blade so far were a lack of stability or increased vibrations of the circular saw blade which caused a high level of noise to be generated. In order to typically reduce noise emissions incisions are introduced into the circular saw blade in the prior art wherein the incisions extends in radial direction from an outer circumference and have several centimeters in length (so called “clef”). This prevents a generation of resonances. Furthermore damping is provided at the incisions by friction with material penetrating the incisions. In the circular saw blade according to the invention with low thickness however it has become apparent that these incisions are counterproductive so that the circular saw blades according to the invention do not have such incisions. They are rather made from a continuous metal disc outside of the teeth.
It is furthermore advantageously when a width of the teeth measured in a circumferential direction of the circular saw blade is less than 20 mm, advantageously less than 15 mm, further advantageously less than 12 mm, most advantageously less than 10 mm and/or a distance of cutting edges of respective adjacent teeth is less than 22 mm, advantageously less than 20 mm, further advantageously less than 18 mm. A reduced width of the teeth reduces a resistance of the circular saw blade when entering the frozen food product to be cut. Thus it is furthermore possible to arrange more teeth at a circumference of the circular saw blade which increases a number of cutting edges arranged at the teeth and thus increases cutting performance of the circular saw blade. Furthermore the saw cut becomes finer.
Advantageously cutting edges of teeth of the circular saw blade are made from hard metal, advantageously from hard metal inserts. Thus, portions of the circular saw blade that are loaded the most during cutting of the food product are particularly strong and wear resistant. When cutting edges of inserts are made from hard metal they can be easily replaced during maintenance.
Thus it is furthermore advantageous when a chipping surface extending from a cutting edge of a tooth is in alignment with a front surface of the respective tooth which front surface adjoins in a direction of a base of a chipping cavity or the chipping surface is in a common plane with the front surface of the respective tooth so that forming chips move into the chipping cavity without restriction or deflection.
Alternatively it can be provided that the chipping surface extending from a cutting edge of the tooth forms an angle with a back side of the insert oriented away from the chipping cavity wherein the angle is between 25° and 35°, advantageously between 28° and 32°.
It has proven particularly advantageous that a wedge angle of the teeth of the circular saw blade is between 48° and 68°, advantageously between 55° and 60° and/or a chip angle of the teeth of the circular saw blade is between 15° and 35°, advantageously between 23′ and 30° and/or a free angle of the teeth of the circular saw blade is between 4° and 16°, advantageously between 8° and 12°.
When a difference between the outer diameter of the circular saw blade and a diameter of a circle on which the bases of the chip cavities are arranged is at least 20 mm, advantageously at least 25 mm, this yields a relatively long teeth and a long chipping cavity. This is advantageous because the chipped material shall be collected in the chipping cavity in order to prevent a smearing during the cutting process. Thus it is positive when a chipping cavity volume is larger than a volume of chipped material.
With respect to a force introduction of the hard metal inserts into the circular saw blade it is particularly advantageous when a base portion of the hard metal inserts oriented towards a rotation axis of the circular saw blade is supported by a lug towards an end section of a front surface of the tooth oriented away from the chipping cavity. The inserts that are typically soldered on can typically be supported at the support lug under load which renders the soldered joint more durable.
According to a particularly advantageous embodiment of the invention a side surface of the circular blade that is oriented towards the slice of the food product that is being cut extends at an angle between 2° and 0.2°, advantageously at an angle between 1° and 0.4° relative to an opposite side surface of the circular blade so that a thickness of the saw blade decreases in radial outward direction wherein the opposite side surface of the circular saw blade advantageously extends at an angle of 90° relative to the rotation axis. Accordingly the circular saw blade respectively extends in a cone shape on one side starting from its center and moving to the outer edges. Thus, the circular saw blade has a reduced thickness at its outer circumference compared to its center. Therefore the circular saw blade penetrates a frozen food product much more easily due to a reduced initial resistance.
With respect to a configuration of the circular saw blade it is furthermore advantageous when the circular saw blade has parallel extending side surfaces in an outer ring portion which extends from an outer diameter of the circular saw blade radially towards the center axis and in an inner circular portion which extends radially outward from a center point of the circular saw blade, wherein the side surfaces of the circular saw blade extend at an angle relative to each other in an inner ring portion which extends between the outer ring portion and the inner circular portion. The outer ring portion is thus typically configured thinner than the remaining portions so that a first entry of the circular saw blade into the food product is simplified. During a further penetration of the circular saw blade into the food product also the one sided beveled portion of the circular saw blade penetrates the food product wherein the beveled portion acts like a wedge which presses the nascent slice away from the food strand. The beveled portion thus opens a cutting gap in the food product which improves the cutting process as such.
Thus it can be an additional advantage when the hard metal inserts protrude in axial direction beyond at least one of the two side surfaces of the circular blade, thus advantageously by an amount between 0.05 mm and 0.25 mm further advantageously between 0.15 and 0.20 mm. The interval between 0.20 mm and 0.25 mm can also be well suited. Thus during the cutting process a minimum gap is created between the side surfaces of the circular blade and the cut food product which reduces or prevents a friction or sticking between the side surfaces and the food product.
In order to maintain durability of the circular saw blade which is typically configured very thin and very hard so that a fracture can occur under excessive forces it has proven advantageous to provide an automatic shut off and/or a reduction of an angular velocity of the arm which are respectively activatable when a threshold for a resistance of the arm during passage of the circular saw blade through the food product is exceeded. In particular when a circular saw blade has been in use for a while its sharpness can decrease so that cutting performance decreases as well. For a constant speed of the arm the chipping performance of the circular saw blade decreases with decreasing sharpness, so that the “feed velocity” through the food product is reduced so that a force applied by the arm upon the circular saw blade is significantly increased so that a fracture of the circular saw blade can occur. A rapid increase of the force impacting the circular saw blade can also occur when foreign objects for example made from metal are disposed in the food product. In order to prevent a fracture of the circular saw blade the automatic shutdown is activated according to the invention so that the arm at which the circular saw blade is supported is either reduced in its angular velocity or stopped completely besides a further rotation caused by inertia, wherein the circular saw blade can continue to rotate. As stated supra a speed reduction of the arm can also be provided so that the arm rotates more slowly hence forth so that the circular saw blade has more time to perform its cut. A combined embodiment of the device according to the invention with a speed reduction for the arm and an automatic shutdown of the arm is also conceivable.
It is furthermore feasible to alternatively or additionally provide a speed reduction and/or an automatic shutdown for the circular saw blade which is also activatable when a threshold value for a resistance of the circular saw blade is exceeded during the cutting process. Typically the circular saw blade and the arm are provided with individual separately controllable drives. A measurement of a torque presently impacting the circular saw blade can be provided by measuring the power draw of the respective drive motor. The same applies for measuring the torque currently impacting the arm wherein the power draw of the drive motor of the arm is used. A measurement of an angular velocity of the arm and/or of the circular saw blade can be performed using a respective impulse generator which is arranged in a drive train of the arm and/or of the circular saw blade.
According to another independent aspect of the invention a cutting material support for supporting the food product to be cut is provided at a rear end of the food product in feed direction wherein at least an upper engagement element of the cutting material support can be brought into form locking engagement with a surface of the food product that is oriented away from a base of the feed portion. Additionally a down holder with at least two contact portions is provided wherein the down holder can be brought in contact with a surface of the food product that is oriented away from the feed portion at the contact portion, wherein adjacent contact portions viewed perpendicular to the feed direction and parallel to a base of the feed portion have a distance from one another which corresponds to a maximum width of an upper engagement element so that the upper engagement element and the down holder are in direct contact with the food product until a last slice of the food product is cut off. This way in particular a leftover of the food product to be cut which remains at an end of the cutting process and which typically tends to flip due to its reduced length is pressed down by the down holder and supported by the cutting material support so that a significantly improved fixation of the left over piece is provided during the cutting process. This combination of the down holder with the cutting material support can also be used for other cutting machines, for example for machines which do not have an orbital drive of the cutting device or which are equipped with a knife instead of a saw blade.
Alternatively or additionally the device according to the invention can be provided with a cutting material support for supporting the food product to be cut at its rear end in cutting direction wherein at least an upper engagement element of the cutting material support can be brought in form locking engagement with a surface of the food product that is oriented away from a base of the feed portion. In order to fixate the frozen strand shaped food product during the cutting process particularly well at least one lower engagement element is provided according to the invention wherein the lower engagement element can be brought into form locking engagement with a surface of the food product that is oriented towards the base of the feed portion. Therefore the at least one upper engagement element and the at least one lower engagement element can be considered as a pincer by which the food product to be cut is supported at its top side and at its bottom side. Due to the fact that the frozen food product to be cut is very slippery and typically includes bones and has an irregular shape it is helpful when special emphasis is put on fixating the food product during the cutting process of the food product. In particular a good fixation of the cutting material is important in order to prevent a wedging of the saw blade in the sawing gap due to an unintentional displacement of the food strand different from the feed direction which could fracture the saw blade. Also this pincer shaped configuration of the cutting material support according to the invention can be used for all cutting machines independently from the type of cutting device or other elements. For this purpose the cutting material support and/or the channel base can be provided with small ribs that are offset from one another and which extend parallel to the feed direction and which prevent a slipping or rotation of the frozen and thus very hard food product.
With respect to fixating the food product it can furthermore be advantageous when at least one upper engagement element and/or at least one lower engagement element is respectively arranged at one arm, wherein both engagement elements are advantageously pivotable about a pivot axis that is oriented perpendicular to the feed direction and parallel to a base of the feed portion in order to impart a clamping force from opposite surface portions upon the food product that is arranged between the engagement elements. Imparting the clamping force upon the food product facilitates reliably supporting the food product and establishing a form locking connection.
Advantageously the cutting material support includes a stop element that is adjustable in feed direction wherein the engagement elements are arranged upstream of the stop element in feed direction. As a function of an individual adjustment of a precise position of the stop element this provides a defined distance between an end of the food product to be cut and the engagement portion of the engagement elements. Thus it can be excluded that the engagement elements engage at undesirable locations and impair the cutting process.
With respect to an embodiment of the cutting material support according to the invention it has proven particularly advantageous when the cutting material support includes a drive element that is arranged between the at least one upper and lower engagement element at distal ends of the arms, wherein the drive element facilitates moving the engagement elements closer to each other by opposite pivoting of the arms, wherein the drive element is advantageously configured as piston-cylinder-unit, advantageously as a pneumatic cylinder or hydraulic cylinder. This provides a mechanism which facilitates applying a tension force upon the food product to be cut.
Additionally the cutting material support of the device has proven particularly useful when it includes a linked rectangle whose corners are formed by both pivot axes of the arms and by two links between ends of the arms that are oriented away from the engagement elements and opposite ends of the drive element wherein one side of the linked rectangle is formed by a drive element with variable length and two adjoining sides of the linked rectangle are formed by sections of the arms wherein furthermore both pivot axes of the arms are arranged at a bearing block that is moveable in feed direction by a feed device. The linked rectangle has proven particularly useful in the device according to the invention for cutting frozen food products since the insertion portion is typically provided with a downward tapering groove in which the food product is run. Thus, the groove for example has a cross section in the form of a trapeze with equal arm length, wherein the short side is arranged at the base of the groove and the long side is arranged at the top of the groove. This groove geometry facilitates that an irregular shaped food product for example configured as a thinning beef leg disc continuously has sufficient support from the groove walls extending at a slant angle so that the food product is laterally supported. Since the arms of the cutting material support include a linked rectangle the arms can impart a pressing force upon the food product, wherein the arms are vertically moveable together. Thus, the engagement elements can follow the position of the food product in vertical direction, in particular when a cross section of the food product changes in the portion of the cutting tool while the cutting process progresses.
With respect to the engagement elements it has proven advantageous that at least one of the engagement elements is configured as a separate element and connected with the cutting material support in a disengageable manner, advantageously in that it is arranged at the associated arm in a disengageable manner. Thus, the engagement elements are replaceable in a quick and simple manner, so that engagement elements with various geometries can be used in particular as a function of respective requirements. The engagement element is in particular made from mandrels or teeth which engage the food product and a component at which the mandrels or teeth are arranged.
Last not least it is appreciated with respect to the device according to the invention that the various features of the dependent claims can be implemented individually by themselves or in any combination in embodiments of the invention.
The object is also achieved by a method including the following feature:
e) rotating an arm which supports a center axis of the circular saw blade about a rotation axis d that is fixated at the frame or performing an oscillating movement about the rotation axis.
The method according to the invention is characterized by the advantages recited supra in a context with the device according to the invention and is furthermore implementable in a particularly simple manner with a device of this type according to the invention.
With respect to details of the method it is provided that a speed nK of the circular saw blade is selected relative to the speed nA or angular velocity of the arm at least large enough so that chips which are generated during a pass through of a tooth through the saw gap that is generated in the food product to be cut have a volume which is smaller than a volume of a chipping cavity that is arranged between two adjacent teeth wherein the speed of the circular saw blade is advantageously greater than 1800 rpm, further advantageously greater than 2000 rpm. By adapting the two speeds in the manner recited supra it is provided that the chipped material can be arranged in the chip cavities before it is thrown out of the chip cavities during rotation of the circular blade. Thus, a smearing of chipped material onto the circular saw blade surface is prevented during the cutting process. The speed or the oscillation frequency of the arm should therefore advantageously be greater than 30 per minute, further advantageously greater than 50 per minute even more advantageously greater than 100 per minute.
It is advantageously provided that the rotation of the oscillating movement of the arm is switched off when exceeding a threshold value for a resistance of the arm when the circular saw blade passes through the food product. As stated supra a risk of breaking the circular saw blade is thus minimized.
It is also possible that the speed nA of the arm is reduced when exceeding a resistance threshold for the arm when the circular saw blade passes through the food product.
It is furthermore advantageous when an upper engagement element of a cutting material support is brought into form locking engagement at a rear end of the food product in feed direction with a surface of the food product that is oriented away from a base of the feed portion and a down holder is brought in contact with a surface of the food product oriented away from the base of the feed portion at a forward end in feed direction wherein the upper engagement element and the down holder are in direct contact with the food product until a last slice of the food product is cut off. This yields the advantage recited supra that in particular a residual of the food product that remains at the end of the cutting process and which typically tends to tip due to its short length is pressed down by the down holder and supported by the cutting material support so that a significantly improved fixation of the residual piece is provided during the cutting process.
Alternatively or additionally the method can be provided so that an upper engagement element of a cutting material support is brought into form locking engagement with a surface of the food product that is oriented away from a base of the feed portion at an end of the food product that is arranged in the rear in feed direction, wherein a lower engagement element is brought into form locking engagement with a surface of the food product that is oriented towards the base of the feed portion at a rear end in feed direction. This yields the advantages associated in particular with the device described supra in an analogous manner.
The method according to the invention and the device according to the invention are subsequently described in more detail with reference to an embodiment illustrated in drawing figures, wherein:
a illustrates an enlarged view of an alternative circular saw blade in a portion of the teeth;
A depth T of the chip cavities 20, which corresponds to half a difference between an outer diameter of the circular saw blade 7 and a diameter of a circle on which the bases 21 of the chip cavities 20 are arranged amounts to 14.7 mm in the instant embodiment.
It is evident in the sectional view illustrated in
The difference in thickness between the inner circular portion KB and the outer ring portion RB1 of the circular saw blade 7 is caused by the fact that the left side in
a illustrates an enlarged representation of an alternative circular saw blade in a portion of the teeth 19 which have a slightly different geometry compared to the teeth 19 of
The inserts 22, which have a length l of 9 mm are inclined so that only their pointed portion at a surface of the teeth 19 is visible and their remaining portion is embedded in the teeth 19. This generates large support lugs 25 where the inserts 22 can be supported under load. The chipping surface 26 of the teeth forms an angle of σ of 30° with a straight back side 53 of the inserts 22. The inserts 22 have a maximum width bmax of 3 mm in their cross section and minimum width bmin of 1.5 mm wherein reducing the cross sectional width is performed continuously over a distance s of 4 mm.
It is evident in particular from
The down holder 16′ illustrated in
With respect to embodiments of the down holder 16′ according to the invention numerous alternatives are conceivable, it is only relevant that a free space analogous to the recesses 49 remains between the contact portions 45, wherein the upper engagement elements 29″ of the cutting material support 17″ can move through the free space, though the contact portions 45, 46 of the down holder 16′ are in direct contact or in engagement with the food product to be cut.
The two upper engagement elements 29″ are respectively configured horse shoe shaped or they are U-shaped, wherein a mandrel 31 is arranged at ends of two elongated fingers 48 wherein the mandrel 31 engages the food product to be cut during the feed process. A base 51 of the U-shaped engagement element 29″ has a large depth t so that the connection devices for attaching the engagement element 29″ at the arm 32′ are arranged at this location.
The lower engagement element 30′ whose configuration is evident from
Last not least
| Number | Date | Country | Kind |
|---|---|---|---|
| DE102014105352.4 | Apr 2014 | DE | national |
